The present invention concerns generally concerns the construction of vehicles such as snowmobiles, all terrain vehicles (xe2x80x9cATVsxe2x80x9d), and other similar vehicles. More specifically, the present invention concerns the construction of an engine cradle for such vehicles.
Snowmobiles, ATVs, and related vehicles (hereinafter, xe2x80x9crecreational vehicles,xe2x80x9d although the appellation should not be construed to be limited only to the vehicles or type of vehicles described herein) often function under similar operating conditions. Despite this, snowmobiles, ATVs, and other recreational vehicles do not share a common design approach or a commonality of components. This is due, in large part, to the different stresses and strains (mainly at the extremes) that the different vehicles experience during routine operation.
As a general rule, the prior art includes few, if any, examples of a common design approach to ATVs and snowmobiles. Primarily, this appears to be due to the fact that these vehicles were designed traditionally from two radically different starting points.
Snowmobile frames traditionally have been constructed with a tunnel and an engine cradle, which are individual elements made from metal, plate-like elements, as shown in FIG. 4. ATV frames, on the other hand, have been constructed in much the same way as motorcycle frames by connecting a number of tubular frame elements to one another.
In the case of snowmobiles, the tunnel and engine cradle combination (referred to herein as the xe2x80x9cframexe2x80x9d or xe2x80x9cframe assemblyxe2x80x9d) traditionally has been made of a very strong but light-weight material such as aluminum. To withstand the forces encountered under normal operating conditions, the individual plate elements of the tunnel and engine cradle have been relatively thick so that they do not bend or buckle under high loads. Unfortunately, this adds significantly to the overall weight of the vehicle.
Moreover, several holes need to be provided at various locations in the engine cradle to accommodate shafts for the drive axle, the transmission, and the gearbox. Traditionally, the holes have been drilled into the engine cradle after its construction. A problem with this construction technique is that the holes may not line up as precisely as the manufacturer would like. In some cases, the manufacturer must expend considerable resources to align these shaft holes before producing the final vehicle product.
In view of the foregoing, one object of the present invention is to exploit the design elements of a snowmobile that are easily and readily transferred to the design of an ATV based on the same basic frame structure.
To that end, one object of the present invention is to provide an engine cradle adapted for receiving an engine that includes a left side wall defining a C-shaped opening therein. The engine cradle also includes a right side wall that is essentially solid and that provides a reflective surface for reflecting heat to the engine when contained within the engine cradle. As would be known by one skilled in the art, the right side wall could define the C-shaped opening and the left side wall could define the wall that is essentially solid. The engine cradle also includes a front wall that is connected between forward portions of the left and right side walls. Finally, the engine cradle has a bottom panel and apron connected between bottom portions of the front, left side, and right side walls.
It is another object of the present invention to provide front, left side, and right side walls that are stamped from a sheet of metal. The holes in the walls are stamped into the metal in the same plane that the walls are stamped from the metal sheet. This assured that the holes align with one another during manufacture of the frame assembly.
One further object of the present invention is to provide an engine cradle where the walls have a thickness of less than about 2.5 mm and, more preferably, about 2.0 mm.
Still another object of the present invention is to provide a vehicle frame with a left side structure and a right side structure. A radiator connects the left side structure and the right side structures to one another at a rear portion. A front wall connects between front portions of the left and right side structures. An engine cradle bottom plate and apron connects to the front wall and forward portions of the left and right side structures to define a cradle adapted to receive an engine. The left side structure, the right side structure, the front wall, and the engine cradle bottom plate are each stamped from a sheet of metal.
It is a further object of the present invention to provide a foot-gripping element on a footrest that includes a jagged portion extending upwardly from the footrest and defining teeth at a top portion thereof. A deflector portion is positioned at an opposite side of a hole through the footrest and is angled downwardly from the footrest to discourage particles from being stirred up and passing through the hole onto a top portion of the footrest.
It is still another object of the present invention to incorporate a heat exchanger into the tunnel. In an alternate embodiment, the heat exchanger is a radiator that extends substantially the length of the tunnel and assists in dissipating heat from engine coolant circulating therethrough.
Still other objects of the present invention will be made apparent by the discussion that follows.